In processes for manufacturing various semiconductor devices, it is important to regularly maintain the horizontal levels of the devices. Particularly, it is very significant to regulate their horizontal levels. For example, an electrical die sorting (EDS) process or a chip sorting process is necessarily performed to determine whether individual chips or dies constituting a wafer have good or bad electrical properties.
In the case of a probe apparatus, the horizontal level of a chuck on which a wafer is placed is very significant. If the horizontal level of the chuck is not properly aligned, a needle of a probe card punches the wafer. Namely, the improper horizontal level of the chuck contributes to a contact error. Thus in the probe apparatus, the horizontal level of the chip is periodically checked and regulated.
In a conventional horizontal level measuring method , after fixing an analog gage to a measuring standard point, five horizontal points are measured by moving a wafer chuck. Since a user must move the wafer chuck, a reliability of measured values is degraded.
Further, the user checks a faulty horizontal level of the wafer chuck and regulates the horizontal level by rotating respective leveling bolts based on the measured value. Therefore, a procedure for checking the horizontal level of the wafer chuck must be iteratively performed.